Carton lock



Feb. 20, 1962 M. B. KENNEDY ETAL CARTON LOCK Filed June 2, 1960 Fig. 2

INVENTORS MANLE) B.Keuu5 y LEWIS B. A EXANDER Fig. 4 IO VAT TQRNEYSUnited States Patent Office 3,621,993 Patented Feb. 20, 1962 3,021,993CARTON LOCK Manley B. Kennedy, Walla Walla, and Lewis B. Alexander,Sunnyside, Wash., assignors to American Can Company, New York, N.Y., acorporation of New Jersey Filed June 2, 1960, Ser. No. 33,574 3 Claims.(Cl. 229-36) This invention relates to an improved locking constructionfor a carton, in which opposed panels or walls of the carton are engagedtogether in a manner to substantially prevent their subsequentdisengagement without mutilation of the carton forming material. Becausesuch a locking operation is, as a matter of economic necessity,frequently required to be performed by high speed automatic equipment,it is essential that the locking operation be accomplished in a mannerwhich does not interfere with the speed of operation and results in alock having the desired characteristics. One problem which arises in aperformance of this locking operation is caused by the relativeflexibility of the paperboard material from which the carton is mostcommonly constructed, the paperboard being sufiiciently flexible so thatstability of the members to be engaged is frequently inconsistent.

It is the principal object of this invention to provide an improved formof locking construction which imparts a greatly improved stability andflexibility to the carton material in the area of the locking elements,and to insure automatically positioning of the locking elements so thatlocking engagement is made certain. Other particular objects andadvantages of the invention will become clear from the followingdescription in connection with the appended drawings, in which:

FIGURE 1 is a plan view of a carton blank incorporating a preferredembodiment of the invention;

FIGURE 2 is a perspective view of a set-up carton made from the blank ofFIGURE 1;

FIGURE 3 is an enlarged perspective view partially cut awa, of thefemale locking element of the carton as it is set up in position forlocking engagement; and

FIGURE 4 is a cross sectional view taken along the lines 44 of FIGURE 3.

Referring first to FIGURE 1, the carton blank of this invention is madefrom a suitable material of foldable yet relatively still composition,such as paperboard, plastic, various laminated materials and the like. Apreferred material, commonly employed, is paperboard having a thicknessof from about .010 inch to .030 inch. The blank is suitably cut andscored along the hinging score lines 1 to 9 inclusive to provide aseries of walls, panels and flaps including front wall or panel 10,bottom wall 11, rear wall 12, top or cover wall 13, locking panel 14,end walls 45, dust flaps 16 and glue flaps 17. Locking panel 14 hasformed on the remote edge thereof an arrow-shaped male element 15 havinglaterally spaced locking barbs 15a at the lateral termini thereof. Frontwall 10 has a female locking element formed therein by longitudinal cutlines or slits and lateral out line or slit 19, the area defined bythese out lines providing a deflectable portion the function of whichwill be explained later herein. Positioned below (FIGURE 2) female cutline 19 is a pair of score lines 18, these score lines being positionedso that their upper ends terminate adjacent the lower ends of cut lines20 and their lower ends terminate adjacent the inner ends of hingingscore lines 1 and 2.

The aforementioned score lines dividing the walls and panels from eachother provide a hinging relationship of these structural elements, sothat the carton may be conventionally set up as shown in FIGURE 2. Inthis position, walls 10, 12 and 45 are erected perpendicularly to bottomwall 11, with glue flaps 17 folded inwardly into superposed positionwith respect to the inner surfaces of Walls 45, to which they may beattached by suitable adhesives as indicated in FIGURE 1, by staples, orby any other suitable means. Obviously, a conventional lockingconstruction whereby flaps 17 were engaged with walls 45, alternativelycould be employed. Dust flaps 16 are then folded to overlie bottom wall11, and cover wall 13 is folded over to close the open top of thereceptacle previously formed.

Referring also to FIGURE 3, it will be seen that as front wall '10 iserected perpendicularly to bottom wall 11, such as by a force A appliedto wall 10, score lines 18 will provide in efiect a stiffening strut,serving to assist in the resistance to this folding motion of theportion of front wall 10 in the immediate vicinity of score lines 18.The interruption 26 in the score line hinge connecting wall 10 to wall11, provided by the spacing beyond out line 19 between score lines 1 and2, further increases the resistance of this portion of front panel 10 tothe folding movement. The presence of female out line 19 prevents thisresistance eflect from extending therebeyond into the area 25 of frontwall 10 above cut wall 19, so that as the pressure is applied to erectfront wall 10 a natural opening of the female locking element results,as graphically illustrated in FIGURE 3.

This automatic full opening of the female locking element provided byslit 19, and increased in magnitude by the presence of slits 24)presents a degree of entrance area which insures the entrance of malelocking element 15, even under conditions of highest speed machineoperation, as cover wall 13, with locking panel positioned substantiallyperpendicularly thereto, is brought into position to close the carton.After release of the plow or other means by which wall 10 is erectedperpendicularly to wall 11, locking means 15 having just been inserted,the natural resilience of the carton material in the area 25 and in thearea laterally just beyond cut lines 20 causes that area to attempt tosnap back, and thus assures engagement of the edges of barbs 15a behindthe terminal edges of slit 19, for positive locking engagement of panel14 to wall 10. It will be seen that with respect to the direction ofentrance of element 15 into cut line 19, score lines 18 lie beyond thefemale cut 19.

FIGURE 4 shows in enlarged section the strut forming characteristic ofscore lines 18, by which a significant stiffness is imparted to wall 10to facilitate opening of the female locking means as previouslydescribed.

Having now described a preferred embodiment of the invention, it is tobe understood that the obvious modifications thereof which will beapparent to those skilled in the art are also intended to be includedwithin the scope of this invention, and that the invention therefore isto be limited only as set forth in the appended claims.

We claim:

1. A carton including a pair of opposed panels to be locked together, awall member to which one of said panels is integrally connected along ahinge line defined by a line of weakness by which said one panel may beresistably hinged to lie at a substantial angle relative to the wallmember, locking means comprising a pair of laterally spaced male memberson the other of said panels and female means in said one of the panelscomprising a laterally positioned cut line the edges of which areadapted to engage edges of said male members for locking enagementtherewith, said hinge line being provided by a score line which isdiscontinuous in at least part of the area beyond said female cut line,the carton also including stiifening means integrally formed into saidone panel beyond said cut line and adapted to facilitate opening of saidfemale locking means by planar separation of the portions of said onepanel lying to opposite sides of said out line for engagement therein ofthe male locking means upon the hingglng of said one panel relative tosaid wall member, said stiffening means comprising a pair of spaced,longitudinally directed score lines impressed into said one of thepanels in the area between said female cat line and said discontinuityof the hinge score line.

2. A carton according to claim 1, in which the terminal ends of saidstifiening score lines adjacent the female cut line are positionedintermediate the ends of said female out line.

4 A, n. a i t s a n 2! f th r, includilig a pair of spaced,longitudinally directed cut lines extending from and connected With saidfemale cut line intermediate the ends thereof, saidtpair of cut linesextending in the direction away from said hinging score line. ReferencesCited in the file of this patent UNITED STATES PATENTS 1,738,744 WalterDec. '10, 1929 1,876,063 Kronenberger A Sept. 6, 1932 2,304,362 HuyeDec. 8, 1942 2,846,132 Carpenter Aug. 5, 1958 2,975,953 Muth Mar. 21,,1961

